Fix Make Unused Not Compiler Specific (#34357)

Summary:
Use of `__attribute__` and `__unused` is compiler specific. Opt for standard `[[maybe_unused]]` instead.

## Changelog

[General] [Fixed] - Remove compiler-specific syntax.

Pull Request resolved: https://github.com/facebook/react-native/pull/34357

Test Plan: Built on react-native-windows.

Reviewed By: cipolleschi

Differential Revision: D38498481

Pulled By: javache

fbshipit-source-id: af43206788f54dda3b747b6417e20096c7d520e8

React/Base/RCTModuleMethod.mm

@@ -91,7 +91,7 @@ static BOOL RCTParseSelectorPart(const char **input, NSMutableString *selector)
 static BOOL RCTParseUnused(const char **input)
 {
   return RCTReadString(input, "__attribute__((unused))") || RCTReadString(input, "__attribute__((__unused__))") ||
-      RCTReadString(input, "__unused");
+      RCTReadString(input, "__unused") || RCTReadString(input, "[[maybe_unused]]");
 }
 
 static RCTNullability RCTParseNullability(const char **input)

ReactCommon/cxxreact/JSExecutor.h

@@ -128,8 +128,7 @@ class RN_EXPORT JSExecutor {
    */
   virtual std::string getDescription() = 0;
 
-  virtual void handleMemoryPressure(__attribute__((unused)) int pressureLevel) {
-  }
+  virtual void handleMemoryPressure([[maybe_unused]] int pressureLevel) {}
 
   virtual void destroy() {}
   virtual ~JSExecutor() {}

ReactCommon/cxxreact/NativeToJsBridge.cpp

@@ -52,7 +52,7 @@ class JsToNativeBridge : public react::ExecutorDelegate {
   }
 
   void callNativeModules(
-      __attribute__((unused)) JSExecutor &executor,
+      [[maybe_unused]] JSExecutor &executor,
       folly::dynamic &&calls,
       bool isEndOfBatch) override {
     CHECK(m_registry || calls.empty())
@@ -85,7 +85,7 @@ class JsToNativeBridge : public react::ExecutorDelegate {
   }
 
   MethodCallResult callSerializableNativeHook(
-      __attribute__((unused)) JSExecutor &executor,
+      [[maybe_unused]] JSExecutor &executor,
       unsigned int moduleId,
       unsigned int methodId,
       folly::dynamic &&args) override {

ReactCommon/cxxreact/SampleCxxModule.cpp

@@ -163,7 +163,7 @@ void SampleCxxModule::save(folly::dynamic args) {
   sample_->save(std::move(m));
 }
 
-void SampleCxxModule::load(__unused folly::dynamic args, Callback cb) {
+void SampleCxxModule::load([[maybe_unused]] folly::dynamic args, Callback cb) {
   dynamic d = dynamic::object;
   for (const auto &p : sample_->load()) {
     d.insert(p.first, p.second);

ReactCommon/jsiexecutor/jsireact/JSIExecutor.cpp

@@ -173,7 +173,7 @@ void JSIExecutor::setBundleRegistry(std::unique_ptr<RAMBundleRegistry> r) {
             PropNameID::forAscii(*runtime_, "nativeRequire"),
             2,
             [this](
-                __unused Runtime &rt,
+                [[maybe_unused]] Runtime &rt,
                 const facebook::jsi::Value &,
                 const facebook::jsi::Value *args,
                 size_t count) { return nativeRequire(args, count); }));